Seat with relative synchronous displacement between back incline and seat incline

Abstract

The chair is of the type with mutually synchronous adjustment between back inclination and seat inclination, namely via a region between a respective zero position of back inclination (R0) and seat inclination (S0) and a respective maximum back inclination and seat inclination. The chair has a substructure (1) which is intended for placing on the floor and on which a base (2) is fastened rigidly. A seat support (6) which has a seat region and a back region is connected to the base (2). Furthermore, the chair includes two backrest bows (3) which are deflectable differently with respect to each other and are fastened on one side to the base (2) and on the other side to the back region of the seat support (6). The two backrest bows (3) are coupled independently of each other to the base (2) on a stationary first axis of rotation (D1). The seat region of the seat support (6) is coupled to the base (2) on a stationary second axis of rotation (D2). The two backrest bows (3) are coupled independently of each other to the back region of the seat support (6) on an elastically deformable third axis of rotation (D3). The back region of the seat support (6) is twistable elastically. The seat support is covered with a cover. In the configuration as an office swivel chair, a height-adjustable pneumatic spring (12) on which the base (2) rests in order to adjust the seat support (6) to a height corresponding to a user's needs and in order to configure said seat support (6) to be rotatable about a vertical axis (V) is arranged in the substructure (1).

The invention claimed is: 
     
       1. A chair with mutually synchronous adjustment between back inclination and seat inclination, via a region between a respective zero position of back inclination and seat inclination and a respective maximum back inclination and seat inclination, comprising:
 a substructure configured to contact a floor; 
 a base fastened rigidly on the substructure; 
 a seat support connected to the base, the seat support having a seat region and a back region; 
 a first backrest bow and a second backrest bow, the first backrest bow and the second backrest bow being fastened on one side to the base and on the other side to the back region of the seat support, wherein 
 the first backrest bow and the second backrest bow are coupled independently of each other to the base on a stationary first axis of rotation; 
 the seat region of the seat support is coupled to the base on a stationary second axis of rotation; 
 the first backrest bow and the second backrest bow are coupled independently of each other to the back region of the seat support on an elastically deformable third axis of rotation; and 
 the back region of the seat support is twistable elastically. 
 
     
     
       2. The chair as claimed in  claim 1 , further comprising:
 a first spring unit which acts counter to the first backrest bow and the second backrest bow; and 
 a second spring unit which is supported at one side on the base in a stationary abutment and which acts at the other side against the first backrest bow and the second backrest bow, the second spring unit being in a parallel connection to the first spring unit. 
 
     
     
       3. The chair as claimed in  claim 1 , further comprising:
 a first spring unit, the first spring unit being adjustable and having a first spring element and a second spring element; and 
 a second spring unit having a third spring element and a fourth spring element, wherein 
 the base is a U-shaped housing having a central part and a first limb and a second limb extending therefrom, 
 the third spring element is arranged in the first limb and the fourth spring element is arranged in the second limb, and 
 the first axis of rotation runs through the central part while the second axis of rotation extends through a free end of the first limb and a free end of the second limb. 
 
     
     
       4. The chair as claimed in  claim 1 , wherein:
 the seat support comprises a first strut and a second strut which extend over the seat region and the back region; 
 upper connecting members through which the third axis of rotation runs are present on the first strut and the second strut in the back region; 
 central connecting members through which a fourth axis of rotation runs are present on the first strut and the second strut in the seat region; and 
 a first cross strut on which front connecting members are located, through which the second axis of rotation runs, is arranged between the first strut and the second strut in the seat region. 
 
     
     
       5. The chair as claimed in  claim 4 , wherein:
 the first cross strut is arranged in a front of the seat region and a second cross strut extends between the first strut and the second strut in a rear of the seat region; 
 the back region is spanned between the first strut and the second strut by a back bow; 
 the first strut and the second strut, the first cross strut and the second cross strut and the back bow form the seat support as joined individual parts, or the seat support is produced integrally as an injection molded plastics part; and 
 the first strut and the second strut respectively have an elastically deformable region between the seat region and the back region. 
 
     
     
       6. The chair as claimed in  claim 1 , further comprising
 a first armrest and a second armrest, the first armrest and the second armrest being articulated on one side on the third axis of rotation and on the other side on a fourth axis of rotation. 
 
     
     
       7. The chair as claimed in  claim 6 , wherein:
 the first armrest and the second armrest have a bearing region extending horizontally from the third axis of rotation and a support region extending upward from the fourth axis of rotation such that 
 a transition exists between the bearing region and the support region; 
 the first armrest and the second armrest support, during a movement of the chair into the maximum back inclination and seat inclination, a damping effect of a first spring unit and a dampening effect of a second spring unit such that during a movement back in a direction of the zero position of back inclination and seat inclination, the first armrest and the second armrest support a restoring force of the first spring unit and a restoring force of the second spring unit; and 
 the first armrest and the second armrest are produced integrally as an injection molded plastics part. 
 
     
     
       8. The chair as claimed in  claim 1 , wherein:
 a stationary fifth axis of rotation on which a pre-adjustment mechanism for adjusting the intensity of a first spring unit is arranged extends through the base; 
 a first spring element and a second spring element have a block-shaped body made of elastomer, the first spring element and the second spring element being arranged on an extension of the first backrest bow and an extension of the second backrest bow; 
 a first displaceable pressure piece and a second displaceable pressure piece are assigned to one of the first spring element and the second spring element, the first displaceable pressure piece and the second displaceable pressure piece being arranged along the fifth axis of rotation on the pre-adjustment mechanism; and 
 the first displaceable pressure piece and the second displaceable pressure piece can be aligned with the first spring element and the second spring element with a selectable degree of congruence by actuation of the pre-adjustment mechanism in order to obtain, during a movement of the chair into the maximum back inclination and seat inclination, a desired damping in accordance with a portion of the first spring element and a portion of the second spring element that are squashed between the extensions and the displaceable pressure pieces, together with an effect of a second spring unit. 
 
     
     
       9. The chair as claimed in  claim 1 , further comprising:
 a third spring element and a fourth spring element of a second spring unit, the third spring element and the fourth spring element being helical compression springs, wherein 
 the third spring element and the fourth spring element are provided with an end piece having a fixing member which receives an end of the third spring element and an end of the fourth spring element thereby forming a first spring assembly and a second spring assembly; and 
 a sixth axis of rotation on which respective end pieces of the first spring assembly and the second spring assembly are articulated extends through an extension of the first backrest bow and an extension of the second backrest bow. 
 
     
     
       10. The chair as claimed in  claim 1 , wherein a first strut and a second strut of the seat support have a groove which runs longitudinally and in which a cover for stretching over the seat support can be fixed. 
     
     
       11. The chair as claimed in  claim 1 , wherein a height-adjustable pneumatic spring on which the base rests is arranged in the substructure, the pneumatic spring being configured to adjust the seat support to a height corresponding to a need of a user and rotate the seat support about a vertical axis.